In the manufacture of pipe and pipe fittings, it is necessary to test pipe for bursting pressure. This is particularly true of fabricated fittings and the like. As an example, there are many feet of welded beads and seams formed in a four way connector even though each leg of the connector may be only two or three feet in length when speaking of pipe in the range of about 10 to 30 inches ID. It is very important to pressure test the pipe or fitting after it has been fabricated. The present invention is an apparatus which assists in this problem.
Other types of pressure test closure equipment are known. One type is temporarily welding a sealing plate over a pipe. The sealing plate can be located on the end of the pipe and temporarily tack welded on the exterior. Another type of pressure seal device utilizes the insertion of a disc into the pipe. The disc is constructed and arranged with a sandwich of components. Solid metal discs which barely fit within the pipe sandwich a seal member such as a resilient ring. As the ring is squeezed and expanded, it comes into contact with the pipe thereby forming a seal. This is achieved by compressing a stack of discs. This requires that at least one of the disc be mounted on a movable stem or spindle so that it can be reciprocated to expand the seal ring.
Another type of mechanism utilizes a set of independent jaws which clamp around the exterior with each jaw made snug against the pipe by means of a screwdriver or wrench adjustment. Each jaw is tightened to a specified torque on the screw or bolt which jams the independent jaw against the pipe.
Representative patents are U.S. Pat. Nos. 3,885,521; 1,746,071; 2,399,544; 2,445,645; 2,480,358; 2,851,061; 3,108,012; 3,125,464; 3,525,111; and 3,703,947.
The present invention overcomes some of the handicaps found in the competitive devices. This device is more expedient at the time of installation and removal. It is expedient by virtue of the fact that it is self-actuating when installed on the pipe. That is to say, the device holds the pipe more firmly as pressure in the pipe is increased. The firmness of the hold increases proportionately with the pressure and accordingly, provides a closure which is held on by a force exceeding that within the pipe tending to expell the plug. This also enables the device to be used with pipe which is not perfectly round. If the pipe is out of round by as much as 1/8 of 1 inch, some of the competitive devices will not operate very well. With this invention, the use of independent gripping mechanisms on the exterior which pivot independently of one another results in the construction of a gripper mechanism which will hold a non-round pipe. The portion of the equipment which perfects the seal is independent from the gripper mechanism.
The present invention is quickly installed and removed. It is installed by pushing the temporary seal mechanism on the end of a pipe or fitting. The only requirement for the pipe is that the end be cut off square, or approximately so, and that the pipe have a certain degree of roundness. The end of the pipe is received in a fitted container having an internal seal ring. The seal ring is positioned against the pipe. Preferably, an external seal is perfected. After the seal is completed around the exterior, the device will hold against fairly low pressures.
The device further incorporates externally located movable gripper means. The external gripper mechanisms are mounted on an external lip which surrounds the tool and extends over the exterior of the pipe. The lip supports by movable links peripheral grippers which extend around a part of the circumference and carry a set of serrations on the interior face. The serrations are sloped so that they tend to bite into the metal. The gripper mechanism is pivoted by the mounting link so that it takes a deeper bite as pressure within the pipe is built up. An increase in internal pressure is conveyed through the present invention to the links and they are slightly rotated. This tendency to rotate jams the serrations all the more firmly against the pipe to hold the pipe in the required position. The rotation mentioned for the links may be minute in ordinary circumstances; however, it is enough to increase the gripper of the device and particularly it resists sliding movement of the gripper means so that the device cannot slide off the end of the pipe. So to speak, it holds more firmly as it is required to hold more firmly.